Problems associated with the weakening and inflammation of the sacroiliac joint, or “SI joint,” are among the most prevalent causes of lower-back pain. Sacroilitis, or sacroiliac joint dysfunction, is inflammation of one or both SI joints that can lead to extensive pain in the lower back region. Causes of sacroilitis include trauma of the lower back from injury, osteoarthritis of the spine, and infection of the SI joint. Additionally, childbirth is a common causative event for sacroilitis, as pelvic widening and expansion of one or both sacroiliac joints associated with vaginal childbirth can lead to spraining of the ligaments associated with the SI joint. Incidentally, the majority of those diagnosed and treated for sacroilitis are women.
The SI joint is the interface between the sacrum and the left ilium or right ilium. The SI joint is a synovial joint having weight-supporting and shock-absorbing properties. The SI joint is further structurally stabilized with a series of ligaments comprising the anterior, interosseous, posterior, sacrospinous, and sacrotuberous ligaments. Pain associated with the SI joint commonly occurs from increased unwanted movement of the joint that increases movement of the sacrum and/or ilium.
According to a study administrating a series of standardized questionnaires to patients undergoing SI joint treatment, sacroilitis contributes to a significant burden on the health status of a patient. Burden on the quality of life associated with sacroilitis is higher than many other disabling medical conditions, including, for example, COPD, coronary heart disease, and angina (Cher D., et. al. 2014. Sacroiliac joint pain: burden of disease. Med. Devices: Evidence and Res. 7:73-81). The economic impact in the U.S. of annual expenditures associated with chronic back pain is also significant, with approximate costs ranging from $12 billion to $90 billion in direct costs, and $7.4 billion-$13.9 billion in indirect costs (Dagenais, S., et. al. 2008. A systematic review of low back pain cost of illness studies in the United States and internationally. Spine J. 8: 8-20). The prevalence of SI joint pain varies from 15% to 30% of patients having lower back pain (Szadek K M. et. al. 2009. Diagnostic Validity of Criteria for Sacroiliac Joint Pain: A Systematic Review. J Pain. 10(4): 354-368). In some cases, fusion of the SI joint is an important option for patients with lower back pain.
In some cases, fusion of the SI joint is an important option for those suffering lower back pain. Fusion of the SI joint can effectively treat SI joint dysfunction that directly results from SI joint disruptions and degenerative sacroilitis. Methods and procedures to surgically accomplish a SI joint fusion are regularly performed as needed to stabilize the SI joint and relieve painful symptoms caused by SI joint disruptions or degenerative sacroilitis.
Furthermore, there is generally a demand for surgical procedures that are minimally invasive. As evidenced by retroactive studies comparing the minimal clinically important difference (MCID) measurements, recipients of a minimally invasive SI joint fusion procedure statistically had greater improvements in lower back pain alleviation (as measured by Oswestry Disability Index (ODI)), less blood loss, decreased operation time, and decreased length of hospital stay as compared to recipients of open anterior SI joint fusion procedures (Ledonio C G, et. al. 2014. Comparative effectiveness of open versus minimally invasive sacroiliac joint fusion. Med. Devices: Evidence and Res. 7: 187-193; Ledonio C G., et. al. 2014. Minimally invasive versus open sacroiliac joint fusion: are they similarly safe and effective? Clin. Orthop. Relat. Res. 472(6): 1831-1838). However, no surgical intervention adequately and securely fuses the SI joint without problems associated with prior art procedures, such problems including a substantial level of trauma, pain and a long recovery time. Many traditional methods and procedures associated with SI joint fusion require open, non-minimally invasive procedures, often causing an elevated level of trauma, greater pain and a longer recovery time for the subjects of such methods and procedures.
A variety of forces impact the hip area. For instance, the SI joint is responsible for supporting the weight of a person's body. Moreover, anatomical features associated with and located within and near the hip area must facilitate a great deal of movement. Traditional methods often involve the placement of instrumentation in the lumbar spine medial to lateral to the sacral iliac joint. The reliance upon a single screw to secure the SI joint, as associated with several prior art procedures, is often insufficient to effectively stabilize the SI joint. Although a plurality of anchoring implants have also been used within the SI joint area, as disclosed in U.S. Pat. No. 8,734,462 and elsewhere, the weight and movement forces that the various anatomical structures related to and near the hip area must face can potentially lead to a loosening of the screws and/or anchoring implants associated with such prior art surgeries.
Often, the failure of a SI fusion results from the utilization of previously known methods where devices placed in association with such methods will break. Such breakage occurs because of the excessive forces associated with the sacral iliac joint and anatomical structures located near the hip area. Previously known methods fail to adequately and effectively address these forces.
Because of the excessive forces the SI joint experiences, inadequate SI joint fusions deriving from previously known methods can lead to a variety of problems. After a typical previously known surgical procedure intended to address problems associated with the SI joint, mechanical stress on the bone surrounding the SI joint and anchoring implants placed during such procedure may further degrade the bone surrounding the anchoring implants, leading to pseudoarthrosis, costly and risky return surgery, complications, and failed clinical outcome. Such problems also include without limitation the failure of associated instrumentation, the breakage of associated instrumentation, and continued undesirable motion of the SI joint.
The anatomical structure of the SI joint, bone structure, spacing in association with the SI joint and resultant accessibility to the SI joint may vary among differing patients. Several previously known minimally invasive methods and procedures require the placement of an implant. However, in some cases, the SI joint space may not be sufficiently accessible to accommodate such an implant given the anatomical structure of a patient.
The more recent laterally-placed procedures allow for implants to be placed across the joint space. Recent developments in technology associated with bone fusing materials including bone graft and bone graft substitutes, enable the strengthening of two pieces of bone. Many such procedures involve the full decortication of the articular surfaces of a joint prior to filling the joint space with bone graft and bone graft substitutes. However, many previously known methods and procedures related to the SI joint fail to take advantage of such recent developments in technology. Such methods and procedures often fail to effectively and adequately accomplish bony fusion using allograft, auto graft or structural implants within the joint space. Some prior art procedures and methods fail to effectively incorporate the use of bone or bone substitutes placed deep within the joint, and thereby often result in suboptimal bone fusion, breakage of instrumentation and pseudoarthrosis. Some methods and procedures involve the placement of bone grating through or in the region of the sacral iliac joint, however a related problem is that the placement of the bone generally does not take place deep into the joint. As a result, poor sacral iliac fusions thereby result from the suboptimal placement of bone.
For example, a United States patent (U.S. Pat. No. 8,734,462) specifically discloses the use of anchoring implants comprising porous plasma coated titanium to facilitate the fusion adjacent to the anchoring implants within the embedded bone. Yet, in such prior art, the problem of potential movement between the sacrum and ilium after the surgery remains unsolved. Such previously known methods and apparatuses fail to take advantage of the benefits associated with the cleaning and decortication of the articular surfaces and the addition of bone graft materials within the joint space. A previously unsolved problem therefore is a failure to effectively combine the use of biological grafts within the SI joint with mechanical compression of such joint.
Further, some previously known methods and procedures associated with the SI joint lack the percutaneous placement of screws, where open placement of screws is more common. The trauma associated with open placement of screws associated with prior art procedures causes an elevated risk of nerve, abdominal, and vascular injuries, excessive tissue trauma, hematomas, and infections of soft tissues.
Additionally, some of the more recent techniques do not allow for the direct visualization of the bony joint surface, which is considered a preferred method of surgery in some cases and often a requirement mandated by insurance companies to receive reimbursement for fusion procedures. Moreover, there is a risk that prior art procedures and methods leading to a high incidence of pseudoarthrosis, instrumentation failure, and poor clinical outcomes.
While improvements have been made in decreasing the invasiveness of the minimally invasive SI joint surgeries, previously known techniques and methods associated with minimally invasive SI joint surgeries still pose a significant risk for complications. For example, depending on the site of the incision, the chance of hematoma (collection of blood outside of blood vessels) and/or infection increases with the size of the surgical incision. While previously known minimally invasive SI joint procedures have smaller incision sites than open anterior SI joint fusion procedures, the incisions associated with such minimally invasive SI joint procedures still feature lengths between 3 cm and 5 cm or longer. Therefore, such incisions and associated instrumentation related to previously known minimally invasive SI joint procedures have a significant potential to cause damage to tissue, nerves, and bone structures. These also lead to a substantial risk of hematoma and/or infections during and after surgery. Furthermore, by creating a larger incision site, the larger incision site becomes more problematic in cases where the entry site for the corresponding implant needs to be changed during the surgery.
More recently, there has been progress in the field of unilateral SI joint fusion procedures wherein either the left SI joint or right SI joint is stabilized one at a time or in conjunction during the same operation. Progress made in minimally invasive SI joint fusion approaches, as described in the provisional U.S. patent application, U.S. 62/068,602, in general, provide vast improvements as compared to typical prior art unilateral SI fusion procedures. For example, in U.S. patent application, U.S. 62/068,602, the creation of a small incision (approximately 1 to 2 cm), and corresponding instruments that are able to access the SI joint through said small incision aperture, generally reduces nerve/tissue/blood vessel damage, hematoma and/or infections during and after surgery, as compared to prior art inventions that require larger incision openings. Moreover, the decortication of SI joint material, and further filling the decorticated SI joint space with bone fusion material prior to mechanically securing the sacrum and ilium with a stabilizing device, enable added stability to the SI joint. Therefore, U.S. patent application, U.S. 62/068,602, in general, reduces the number of steps, reduces the number of instruments, decreases the size of the surgical wounds, and increases the stability of the SI joint as compared to typical prior art SI Fusion procedures.
In some cases, a patient, insurance provider, and/or doctor may elect to perform a single unilateral SI joint fusion, on just one side of the hip. However, it has been observed that approximately one in five patients have complained of bilateral pain, or pain in both the left and right SI joints. In such cases, doctors elect to perform SI joint stabilization of both SI joints. Of patients that have undergone single unilateral SI joint fusion, some patients post-operatively complain of discomfort and/or pain related to the SI joint on the other side. This additional discomfort and/or pain may occur because of the imbalance of the stabilization when only one SI joint is secured. In typical cases, patients may require further surgery to stabilize the SI joint located on the other side to reduce said discomfort and/or pain.
Prior art SI joint fusions that aim to simultaneously secure both the left and right SI joints, wherein both SI joints are stabilized simultaneously during a single operation, has been described. The Dorsal Bilateral Interlocking Technique stabilizes the SI joints by placing an external fixator between the anterior-superior iliac spine of both ilia such that said fixator secures both ilia on the posterior side of the hip. The SI joints are further stabilized by placing lag screws to secure an ilium to the sacrum in a posterior-lateral to an anterior-medial direction. The process of securing both the left and right SI joints, has been previously reported to be ineffective. In one particular retroactive analysis of a cohort of patients that have undergone a Dorsal Bilateral Interlocking SI joint Fusion, the majority of the patients of the cohort did not have clear or any SI joint fusion, and only temporary or no improvements in symptoms or activities of daily living (Schutz, U and D. Grob. 2006. Poor outcome following bilateral sacroiliac joint fusion for degenerative sacroiliac joint syndrome. Acta. Orthop. Belg. 72: 296-308.). Furthermore, the Dorsal Bilateral Interlocking Technique and other prior art procedures are generally invasive and require a large surgical wound (typically a 10 to 15 cm incision) of the posterior region of the body, wherein the large surgical wound has significant potential to cause damage to tissue, muscle, nerves, and bone structures, and access to the appropriate spinal structures to achieve fusion further requires temporary displacement and/or removal of tissue, muscle, nerves, and other bodily structures. An obvious side-effect to these invasive procedures is that they have substantial risk of causing hematoma and/or infections during and after surgery due to the large size and great impact to the surgical site. Therefore, there is a need for a minimally invasive procedure that simplifies stabilization of both the left and right SI joint, and associated devices that enable said stabilization.